1. Field of the Invention
In at least one aspect, the present invention relates to methods for protecting data in computer networks, and in particular to methods for revoking a system administrator's access to an encrypted file system.
2. Background Art
As businesses become more dependent on the electronic storage of information, security and preservation of such electronically stored information is of paramount importance. Methodologies that are useful in limiting access to electronically stored information include encryption, biometrics, access devices, and the like. While encryption protects encrypted data from being accessed by someone not in possession of the decryption key, the greater the number of individuals having access to the decryption key, the greater the potential is for such a key to fall into the wrong hands.
Certain situations exist that require key management among a plurality of administrators. To better facilitate key management for such situations, methodologies have been described that require a quorum of system administrators to access secured electronically stored information. For example, in Adi Shamir, How to Share a Secret, Communications of the ACM, November, 1979, volume 22, number 11, a method is discussed for dividing data into a number of portions (n) such that the data is reconstructable from a defined number of portions (k), even if k is less than n. In accordance with this strategy, complete knowledge of k−1 pieces reveals absolutely no information about the encrypted data. Such a scheme enables a cryptographic system that can limit access to information, and yet recover data even when several portions are lost or stolen.
Although such methods are useful in limiting access to sensitive information, there are still a number of concerns with the known prior art technologies. For example, electronic information is typically highly replicated thereby making it nearly impossible to erase all copies of the information. Moreover, terminated or revoked system administrators cannot be relied on to return smart cards or to act in an ethical manner. A quorum of such users may inappropriately access secured information.
Accordingly, for at least these reasons new methods for securing critical electronically stored information are desirable.